Polycrase

Polycrase

Polycrase or polycrase-(Y) is a black or brown metallic complex uranium yttrium oxide mineral with formula: (Y,Ca,Ce,U,Th)(Ti,Nb,Ta)2O6. It crystallizes in the orthorhombic system with typically radial prismatic crystal form. It has a Mohs hardness of 5 to 6 and a specific gravity of 5. It is radioactive due to its uranium content (around 6%). It occurs in granitic pegmatites.

It was first described in 1870 at Rasvag, Hidra (Hittero) Island, near Flekkefjord, Norway. It is found in Sweden, Norway, and the United States.

References

* [http://www.mindat.org/min-3257.html Mindat with location data]
* [http://webmineral.com/data/Polycrase-(Y).shtml Webmineral]


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